And they take in too many refined grains, saturated fats, added sugars and salt.

What to do? Here are 5 types of foods you can add today to give your diet a boost.

Dark green vegetables top the list. Make a point of eating choices like spinach and other greens, broccoli and Brussels sprouts.

Next are legumes. Choose from the many varieties of dried beans, lentils and peas. They're great in dishes from hot casseroles and stews to cold salads.

Serve fish or shellfish in place of some of the beef, pork and even poultry in your diet. Two servings a week of fatty fish, like salmon, are ideal.

Nuts, seeds and soy products are other protein sources that can also substitute for traditional meat.

The U.S. Dietary Guidelines for Americans state that the type of fat you eat is more important than the total amount. And the guidelines recommend replacing saturated fats like butter and lard with mono- and poly-unsaturated fatty acids, found in plant-based oils as well as fatty fish. While olive oil is great, try other varieties like safflower, grapeseed and walnut oils.

Keep in mind that you don't have to revamp your diet all at once. Slow and steady changes are more likely to stick.

More information

For details on the latest dietary guidelines, with details on healthful choices from every food group, visit Health.gov.